At present, the implementation of the point-to-point chat technology is mainly based on the GPRS (General Packet Radio Service) technique in the internet or the mobile communication. Point-to-point chat based on the internet requires various network resources, while point-to-point chat based on GPRS via IP (Internet Protocol) requires the support of GPRS data networks.
USSD (Unstructured Supplementary Service Data) is a new interactive data service based on GSM (Global System for Mobile Communications) networks. Using the USSD technology to transmit data does not need large-scale modification of existing mobile networks, therefore the cost is low and the response speed is fast. Operators can flexibly launch various USSD function services for specific situations of local networks to provide services for mobile users conveniently. The USSD technology is mainly used for various value-added services of mobile communication, such as account query, service customization, information query and confirmation, etc.
At present, compared with a data transmission mode based on the internet or GPRS, the USSD technology has great advantages in cost and application mode. In addition, most operators provide a USSD access function, and mobile communication networks can support USSD protocols as well. However, various advantages of the USSD technology in message transmission function have not been utilized fully, and application of the USSD technology in the field of point-to-point chat is still a blank.